a) Field of the Invention
This invention relates to a plant cultivation mat (or grass growing mat) to be laid on the roof top, veranda, terrace, etc. of buildings (in particular, an artificial ground) for growing various plants such as, especially, ground-covering plants like lawn, etc., grasses, flowers, vegetables, and so forth, and to a method for laying such plant cultivation mat.
b) Description of Prior Arts
It has been the conventional practice that, when cultivating or growing plants at a location having flat laying surface such as the roof top, veranda, terrace, etc. of buildings, a water-prevention layer and a root-protecting layer is formed, or a sheet is further laid thereover, and then soil is spread over the sheet to cultivate ground-covering plants such as lawn, grasses and shrubs, vegitables, and so forth (vide: for example, laid-open gazette of Japanese Patent Application No. 4-99411).
With the abovementioned method of spreading soil, however, there arises necessity for providing outfits such as water-prevention layer, etc., which give rise to various problems such that the equipment can hardly be adopted in those existing buildings, while cost to be borne would increase when it is adopted in new buildings.
Furthermore, a large-scaled working becomes necessary for utilization of the abovementioned plant cultivating facility, which requires enormous amount of time and labor.
On the other hand, the life of the water prevention layer is, in general, said to last from ten to fifteen years, which would require removal for replacement of the layer at every time its service life is ended. Besides its service life, when there occur unexpected damages to the water-prevention layer and the laying surface of the plant cultivation mat during the plant cultivation work, it becomes also necessary to remove the plants under cultivation and the soils for cultivation with a view to repairing such water prevention layer from leaking. Again, enormous amount of time and labor are needed for this removing work.